A masochistic Hollywood decree insists that press agents must be depicted on screen as loathsome toadying creatures, and movie moguls as vulgar, mercenary despots. Walter Seltzer, who has died aged 96, was both a press agent and a producer, but he failed to conform to either of the self-perpetuating stereotypes. As a press agent he was persuasive rather than pushy; as a producer, he believed in consensus decision-making.

Undoubtedly his greatest achievement as a press agent was in his promotion of Marty (1955), a gentle, small-scale study of the mundane with no star names. Seltzer believed so much in the Harold Hecht/Burt Lancaster production that the promotional campaign for the film was more expensive than the film itself: $400,000 compared to $343,000. Among Seltzer's tactics was his sending prints of the film to members of the Academy of Motion Picture Arts and Sciences, before the final Oscar nominations were made, now a common practice of lobbying with DVDs. "We offered to send a 16mm print of the picture, a projector and a projectionist to the home of anyone who would invite 20 academy members to a screening," Seltzer recalled.

Marty won best film, best director (Delbert Mann), best screenplay (Paddy Chayevsky) and best actor (Ernest Borgnine), and made a huge profit. Seltzer's campaign had turned the modest production of a simple love affair between a Bronx butcher and a plain schoolteacher into a "sleeper" hit, the first film to which that epithet was applied.

Seltzer, born in Philadelphia, came from a movie-business family. His father was a pioneering film exhibitor, and his two brothers worked in the industry, Frank as a producer and Julian as a film studio advertising director. After attending the University of Pennsylvania, Seltzer went to Hollywood in 1935 as a publicist for MGM at a time when the studio could boast that it had "more stars than in the heavens". He provided titbits on many of the stars to the influential gossip columnists Hedda Hopper and Louella Parsons.

After serving in the Marines for four years during the second world war, Seltzer returned to Hollywood as director of publicity at Hal Wallis Productions, whose films were released by Paramount. It was there that he met Lancaster, while publicising three of his movies, Come Back, Little Sheba (1952), The Rose Tattoo (1955) and Gunfight at the OK Corral (1957). In the meantime, Lancaster had formed his own independent company with Hecht and later James Hill. Seltzer helped promote the company's films, including Marty and Sweet Smell of Success (1957), in which Tony Curtis portrayed a slimy press agent.

In 1959, Seltzer became a producer when he joined Marlon Brando's Pennebaker Productions. He was executive producer on Shake Hands With the Devil (1959), starring James Cagney. Seltzer was also executive producer the following year on the troubled production of One-Eyed Jacks. He was unable to prevent Brando, as star and director, from shooting six times the amount of footage used, and presenting Paramount with a five-hour film. Although the studio recut it, the film remained a rambling, self-indulgent revenge western with superb photography and a brooding Byronic performance from Brando.

Far less problematic was Seltzer's fruitful collaboration with his friend Charlton Heston on seven films as producer. "Though through the years we disagreed violently politically, we were a good team," Seltzer claimed. According to Seltzer, one view they shared was that "the greatest social problem of our time was over-population. We became a little obsessed with the idea."

This was demonstrated by two apocalyptic sci-fi pictures, The Omega Man (1971), in which Heston is the last man on earth after germ warfare between Russia and China, and Soylent Green (1973), where he is a cop among a population of 40 million people in the New York of 2025, who discovers that most of the food consumed consists of the reprocessed bodies of the dead.

Among the other Heston-Seltzer pictures were The War Lord (1965), an unexpectedly successful stab at recreating 11th-century England, with the star in the title role; and two films directed by Tom Gries, Will Penny (1968) and Number One (1969), in which Heston was an ageing cowboy and an ageing sportsman respectively. Seltzer left film-making in 1976, after that year's The Last Hard Men, a western starring Heston as a retired sheriff.

Seltzer then devoted himself to the Motion Picture and Television Fund, which cares for ageing actors and others in the film industry at its 40-acre campus in Woodland Hills in California. He had helped raise millions of dollars for the home where he himself resided in his final years.

Seltzer's wife, Mickell "Micky" Novak, who wrote screenplays and was a publicist for Warner Bros, predeceased him by three years.

• Walter Seltzer, press agent and film producer, born 7 November 1914; died 18 February 2011